Earth auger



De@ N i951 G. A. PETERSEN 2,578,04

EARTH AUGER Filed Aug. 5, 1946 2 SHEETS- SHEET 2 INVENTOR. GERA LD, A. PE rER SEN.

ATTORNEK Patented Dec. 11, 1951 UNITED STATES AT.iizlwr OFFICE 3 claims; (c1. Z55-1o).

This invention relates to power drivenA earth augers particularly intended for digging' or boring holes for telephone and' power. line posts' and the like.

The object'of the' present'inven'tion is" generally to improve and simplify the construction and operation of earth augers of the charactei'ldescribed; to' provide an augerof the' helical type and particularly a double helical type; to provide a double helical type auger which presents two opposed cutting edges; 'to provide removable and reversible cutting blades; to provide a cutting edge having a plurality of spaced apart chisellike teeth so that ashearing'cut is obtained both in a horizontal and in' a vertical plane; to provide au double helical type auger with diametrically opposed cutting' edges and-between' them a cooperating pilot bit; and-further, to provide in conjunction with the double helix a pair of opposed hinged gates to trap and retain dirt when pulling or raisingtheauger out lof the liole.-

The earth auger is shown'` by wayof illustration in the' accompanying drawings which:

Fig. l is a side elevation ofthe earth auger;

Fig; 2 is a side elevationlbut taken atiright angles to Fig'. 1'; u

Fig. 3 is aperspective view of one form of cutting blade;

Fig; 4f shows anotherform of cuttingblade;v

Fig. 5 is a planrviewoffFig. 1,;v Y

Eig. (iisv a bottom view of Fig. l.; Y

Fig. 7 is a diagrammatic view showing the manner inl whichl the pilot bit andthe cutter teeth cut while boring ahole; and

Fig. 8 is a diagrammatic view showing the position of the cutterl teeth. l A

Referring to thedrawings inY detail and particularly Figs. l, 2 and 5 and 6, A indicates a centraly shaft or stem at the lower end of which is suitably secured a pilot bit 2. Welded to the stem or formed integral therewith are a pair of helical shaped blades 3 and 4. These blades are positioned diametrically opposite each other one on each side of the stem and form a double helix,v the function of which will hereinafter be described.

The lower end of each helical shaped bladev is bent downwardly to assume an; angle slightly steeper or greater than that presented` by the pitch of the blades. These bentf ends form seats or supports 5 for cutter bars or blades'of different types as shown in Figs. 3 and 4. The type shown in Fig. 3 consists of a plate G which is bolted or otherwise secured to the seat 5. The forward edge is formed top'rovide a plurality of spaced apart bars 8, each vof which constitutes a 2 support for a chisel-likecutter such as shown at 9, the cutters 9,r 9a andb being suitably secured when appliedV for instance byl welding. The position assumed by the chisel-like cutters is of great importance. By referring to Fig. 8, itwill be noted that as the. auger stem A rotates about its central axis lLthe path -of rotation of the cutter 8' will be that indicated by thev arc I'l, the cutter 9a by the arc l2and the cutter Sl'by thearc I4. lt will further be noted that each cutter is'y disposed with its long axis on an acute angle" with relation to the' radial line indicated at.l l5 and that these acute angles arel not nTy-tang'enttb theA respective arcs Il, f2 and' Ill, but that these angles' vary. The agle'f 'the cutter 9' being ifidicated by the dottedl line l lc-I'lais'tli'e greatest. The angle of the cutter sa is slightly iets while the an'gle` of ithe'cutter' 9b' is thel'e'a'st'. The cutters 9, Sai and S on ea'chcutter blade' travel approximately inl 'a' lhorizontal plane' when the auger is inoperation' and as' the cutters' on' each seat' 5 arespace'd apart, it is preferable to' stagger the cutters slightly'so Ythat the' cutters on one seat 5' will' cut V in paths disposed betv'vee'nv the paths of the" cutter onl the other serat'. Y

It should also be notedby referring to Figsg and 'that'theedg'e's' of the cutters l9, 9a and V9b* assume different angles withlrelationto a horizontal plane. That is (see Fig. 3),each bar-"8 is'` slightly rtwisted' about its longitudinal' axis; so that whenl the chisel cutters 9, 9a andY 9b' are Vapplied, they will assume'differen't angular po'sitions with relation to' ahorizontal plane'.` Thus, when the auger is being rotated, the pilot bit-will' cut or bore-the hole indicated at l-r in Fig Tlf,- while the cutters 9, -S and 9b will 'cut-angular sur-faces such as indicated-at@ Saa andbb. As the cutters onthe'oth'er blade are staggered with relation to the cutters onlthe first named blade, theare'as I- and? I8 ybetween the cuts 9', Saay and ebb' willbe cut on similar angles by the' cutters ofthe second name'dblade. Y

From the foregoing it shouldV be' apparent-that the cuttersare Vnot onlyf. disposed on different angles in `a horizontal planewith respect to a radiusl l5, but alsof on differentl angles measured vertically'with relation to a horizontal plane with the result that the cuttingedge` of each 'cutter cuts withl az slicing action in ,bothr ,planesithereby not onlyzdecreasingwear and tear, but alsomaterially increasing cutting. efficiency. Y

The chisel-like cutters are employed in hard and gravel-like formations.- In softer formations such as vearth,.clay, etc., a straight-edged cutter blade 34| may beemployed asfoshownv in; Fig. 4. This blade -by the way is reversible as it is provided with two cutting edges 32 and 33, but whether one or another of the cutting blades is employed, it should be noted (see particularly Fig. 8) that the cutting edge is positioned forward of the radial line I drawn from the axis IU of rotation. For instance, it is obvious that the forward end of the cutters 9, 8a and 9b are set forward of this radial line and if the blade shown in Fig. 4 is employed, the line indicated at |5a will represent the cutting edge and this is also obviously positioned forward of the radial line I5. This forward positioning of the cutters is also important as it increases the tendency of the cutters to form a slicing cut during rotation of the auger, hence further improving cutting eiliciency and reducing wear and tear and requiring less power to operate. Y

In actual operation when the auger is in a hole and rotating, it is obvious that the cutters due to their inclined position, will dig into the material and force it upwardly on to the helical blades 3 and 4, and that these blades due to their helical shape will force the dirt or material upwardly into the hole or in other words into the annular space surrounding the` stem A. When a certain amount of dirt or material accumulates above the auger, it is common practice to lift the auger to remove the dirt, and when doing this, it is found, particularly if the dirt is dry, hard and crumbly, that it tends to slide down the helical blades and back into the hole. To prevent this, a pair of gates 25 and 26 are provided. These gates are hingedly secured as at 25a and 26a to the upper ends of the helical blades and their free ends lift as shown in dotted lines at 25h (see Fig. 2) and thereby permit the dirt to work upwardly when the auger is digging, but they close the moment the auger is lifted as the free ends overlap and will rest at the points indicated at 21 and 28, thus trapping the dirt and permitting substantially complete removal thereof when the auger is lifted.

By referring to Fig. 5 it will be noted that the helical blade 3 extends from the point 3a to the point 3b a distance slightly more than ninety degrees of a revolution about the stem A. yTo be more exact the blade extends through an angle of from 110 to 125 degrees; the reason therefor is that it is desirable to leave as large an entrance opening to each helical blade as possible so that larger stones, rocks and chunks of material may pass through. For instance when digging in gravel formations fairly large stones. three or four or more inches in diameter, are often encountered and dislodged by the chisellike cutters. These stones when dislodged are forced upwardly over the cutters and the plate 6 and when they engage the under side of the gates, they lift them and the stones will accordingly pass on to the helical blades which will impart a further lift in an upward direction into the hole. It is for the above reason that each helical blade should be maintained as short as possible as the length and the pitch of the helical blades determine the size of the entrance openings covered by thegates and therebyv the size of stones or rocks that may be handled.

In actual operation an auger of this character has been found exceedingly eiiicient for digging in gravel and other hard formations, and when the blade shown in Fig. 4 is employed, clay and other similar sticky formations may be efllciently handled. As both the blades shown in Figs. 3 and 4 are removable or detachable, it is obvious that they may be removed or replaced from time 4 to time by re-sharpened cutters, and so may, of course, the pilot bit, and while this and other features of the invention have been more or less specifically described. and illustrated, it should be understood that changes may be resorted to within the scope of the appended claims and that the materials and finish of the several parts employed may be such as the experience or judgment of the manufacturer maydictate or varying conditions or usesmay demand.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. An auger of the character described comi prislng a central stem whereby rotation is imparted, a pair of helical shaped blades secured to the stem, one on each side thereof and opposite each other, said blades forming a double helix, and a plurality of chisel-like cutters secured to the lower end of each helical blade, there being cutting edges on said cutters, said cutters being spaced apart, being disposed generally to continue said helix and being twisted to dispose the cutting edges at angles to said helix, the cutters on one side of the auger being radially staggered with relation to the cutters on the opposite side.

2. An auger of the character described comprising a central stem, a pair of helical shaped blades secured to the stem, one on each side thereof and opposite each other, said blades forming a double helix, a pair of plates each having a plurality of bars thereon said bars having the general conformation of said helix, means for securing said plates to said blades with said bars substantially continuing said double helix, and cutters on said bars, the cutters and bars being twisted to dispose the cutters at angles to said helix and the cutters on one of said plates being radially staggered with respect to the cutters on the other of said plates.

3. An auger of the character described comprising a central stem having an axis, a pair of helical shaped blades secured to the stem, one on each side thereof anddopposite each other, said blades forming a double helix, a pair of plates each having a plurality of substantially straight bars thereon, saidbars on each of said plates having the general conformation of'said helix and ending at diierent radial planes, means for securing said platesto said blades with said bars substantially continuing said double helix, and cutters on said bars, the cutters and bars on one of said plates being radially staggered with respect to the cutters and bars on the other of said plates, and each of said bars and cutters when seen in the direction of said axis being approximately tangent to its arc of travel about said axis.

GERALD A. PETERSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

